As long as you are conversant with RAW (rules as written) and know why you are selecting optional rules or house rules to get Your Campaign to where you want -- and it isn't nearly a total re-write -- I don't have a problem. In fact I encourage it!

This hobby encourages DIY (do it yourself), so naturally adaptation to one's vision makes sense. But one should also br conversant in other RPGs, too, I believe. Sometimes different mechanics are like different orchestral instruments, there's a reason for their aesthetics; basicall don't try to twist a piano into a trumpet, drum, or bassoon, just learn that there's other instruments out there.

Basically 'System Matters'... to a point. Don't need to reinvent already-made instruments out of another's parts. But you can't be afraid to personalize the instrument's sound to make your own music.

Depending on how rules-heavy the system is.
Something like White Box, DM inevitably has to house rule.
Mythras, not so much.

If the players don't trust the DM to make fair house-rulings, then get new players or players find a new DM.

One of the drawbacks of player agency becoming such a big part of new systems:  the players get to decide if the rules fit their agenda.

Forget that noise.  If they want that privilege, then freakin' take on the DM role and all its responsibilities and go active instead of passive in the game.

I've never had much problems with players accepting my houserules, because they're almost invariably favorable to the players somehow (and technically to enemies too, since they usually apply for them as well), or at least neutral. Most of them are just stuff like "no spell memorization", extra customization options, or "I don't keep track of alignment/don't care", and almost no one has any problem with that.

I do tend to houserule D&D more than other systems, though, since other systems tend to have more options or flexibility, and less rules I object to (I've yet to play a non-D&D game with spell memorization, for example).

I would also interject that on-the-fly dm fiat should not count as houserule, for example, back in 3e if a player cast wall of iron for its usual intended purpose (blocking a ravine or constructing a fortress) i let run as written, but if a player moved to harvest the wall to make money i would have it instantly begin to rust away, lasting roughly 1 hour per caster lvl before being rust in the wind, not worth writing into a list of houserules but certainly a curb on abuse in the moment that i think most would find acceptable (and to hell with them if they don't!) lol.

Also on this subject i hold that the "oberoni fallacy" is itself a fallacy, since rule zero is a rule and not a houserule and its application (such as the example above) enforces balance. Bear in mind that when I look at these kids today who cried about RaW and balance and broken back then, I see that they've been doing things this whole time such as multiclassing paladin/assassin, cleric/druid etc; treating spells and class features and feats and skill and such as magic the gathering cards, wholly detached from any roleplay, just mechanical maguffins to facilitate their cheese, creating the very issues themselves but accepting no culpability in it...that such people would stink eye your DM'ing or houseruling is laughable to the umpteenth degree.